1. Field of the Invention
The present disclosure relates to pulse detection, and more particularly to pulse detection using a bandpass filter with a gain stage.
2. Description of Related Art
Multiband image sensors can be used for concurrent capture and readout of images with signal content over a variety of temporal frequencies. However, conventional imaging pixels are limited in their ability to distinguish signals based on their temporal frequencies. For example, an image may include a short duration signal, such as a laser pulse, and a constant signal, such as reflected sunlight. A conventional pixel is limited in its ability to distinguish and accurately sense these signals that have very different temporal frequency content.
In a military application, laser coded pulses can be applied to an object being imaged to identify the object in the image. The objective is to generate a single image that shows the object identified based on the laser coded pulses. There is a large difference between the signal frequency associated with the laser pulses and the signal frequency associated with the imaged object. It is often the case that absolute signal strength of a laser pulse signal in photons is much less than a background signal strength of the imaged object. In conventional imagers, a single pixel is unable to capture an image of the laser with adequate sensitivity because it cannot distinguish the laser pulse signal energy from the image background signal energy.
While conventional methods and systems have generally been considered satisfactory for their intended purpose, there is still a need in the art for pixels to have increased bandwidth for multiband sensing to enable sensing signals with high temporal frequency content, such as signals associated with laser pulses, with high sensitivity while simultaneously imaging a background scene with low temporal frequency content. There is a need for a single pixel to be able to capture an image of a laser output and an object being targeted by the laser. The present disclosure provides a solution for this problem.